The cells show plumpy hyperchromatic nuclei with moderate pleomorphism some intranuclear pseudoinclusions are also noted.

Nerve sheath differentiation in the form of elongated, slender wavy nuclei.

Scanty cytoplasm.

On Histopathology the case was diagnosed as Malignant Peripheral Nerve Sheath Tumor.

The morphological features of MPNST are very variable. The 2 most common patterns are the spindle cell and epithelioid cell patterns. Cases showing fibromyxoid like morphology and Hemangiopericytoma like features are reported.

“The majority of MPNST are diagnosed as spindle cell sarcoma or pleomorphic sarcoma with FNA. The cellular features may suggest MPNST but a diagnosis may be difficult, even with the help of adjunctive methods. IC may be of diagnostic help if S-100 protein is positive. The positivity in MPNST is typically focal, extensive staining favours a cellular schwannoma. negative staining with desmin, SMA and muscle-specific actin excludes smooth muscle tumours and negative staining with cytokeratin, EMA and CD99 excludes synovial sarcoma”. The Cytology of Soft Tissue Tumours Dr. Mi1ns Akerman Dr. I-Ienryk A. Domanski

Helpful features include sharp radiating pain in FNA aspiration, Relation with major nerve trunk and history of Neurofibromatosis type 1 .